Counterbalancing device.



R. D. GARDNER.

COUNTERBALANCING DEVICE.

APPLICATION FILED NOV. 23. 1915.

1,224,629. Patented May 1, 1911.

Sec/12:11 07? NN.

Frg. 3.

IN VEN TOR.

A TTORNEY.

RANDALL D. GARDNER, OF BOSTON, MASSACHUSETTS.

COUNTERBALANCING DEVICE.

Specification of Letters Patent.

Patented May 31, TQTZ.

Application filed November 23, 1915. Serial No. 63,048.

To all whom it may concern:

Be it known that I, RANDALL D. GARDNER; of Boston, in the county of Suffolk and State of Massachusetts, have invented a new and useful Counterbalancing Device of which the following is a specification.

The main object of my invention is to provide a simple accurate and light counterbalance for lift drawbridges or other moving loads.

My invention consists partly in means for shortening the travel of the counterbalance as well as for apportioning the weight of the same in its effect upon the moving load so that the load and counterbalance will balance each other in all positions.

Other features of my invention will be pointed out below.

I disclose my invention as applied to a lift bridge but it is applicable to many other uses inwhich it is desired to balance a moving load.

In the drawing:

Figure 1 is an elevation of a lift bridge embodying my invention;

Fig. 2 is an end view of the same, with the bridge lowered; and

Fig. 3 is a partial section on line N N of Fig. 1.

Bridge member Al is pivoted at w in the lower part of tower B. Counterweight C1 is connected to bridge member A1 by flexible members f which run over sheaves g and h mounted on the tower and run under sheaves 01 which are mounted on links a which are pivoted at b to tower B. At the outer ends of links a are pins (2 which are connected to the counterweight C1 by links 6, c.

Any suitable mechanism for moving the bridge may be provided and I show a toothed segment A engaged by pinion y which may be rotated by hand or otherwise.

When the bridge is closed counterweight C1 exerts its full weight upon the bridge Al through the members f. This is true at the beginning of the opening of the bridge but as soon as the counterweight has dropped a certain distance the links 6 6 become alined and as the counterweight descends it pulls with it the sheaves 01 which deflect members f thereby gradually diminishing the effect of the counterweight upon the moving bridge Al. The position of the parts at A2, 02 and 02 indicate this operation. AS

the counterweight descends farther the members 7 are deflected more and more thereby decreasing the drop of the counterweight C1 and at the same time diminishing the pull upon the bridge A1 until when the bridge is fully open with the parts at A3, 03 and C3, the horizontal pull upon the bridge by the counterweight C1 is practically eliminated.

The sheaves 01 is an auxiliary member acting to deflect the flexible means and also to take part in supporting a portion of the weight of the counterweight.

Vhat I claim is:

1. A counterbalancing device comprising a pivoted member to be lifted; a counterweight; two membcrs spaced apart; flexible means connecting said pivoted member and counterweight and passing over said spaced members; an auxiliary member between said spaced members and in engagement with said flexible means; and means operated by the counterweight to move said auxiliary member to deflect said flexible means.

2. A counterbalancing device comprising a pivoted member to be lifted; a counterweight; two members spaced apart; flexible means connecting said member and counterweight and engaging said spaced members; an auxiliary member between said spaced members and in engagement with said flexible means; and means connected to said counterweight and said auxiliary member ,through which the counterweight moves said auxiliary member to deflect said flexible means.

3. A counterbalancing device comprising a pivoted member to be lifted; a counterweight; two members spaced apart; flexible means connecting said member and counterweight and passing over said spaced mem bers; an auxiliary member between said spaced members and in engagement with said flexible means; a pivoted arm carrying said auxiliary member; and means connecting said counterweight and pivoted arm through which said auxiliary member is moved to deflect said flexible means.

4. A counter-balancing device comprising a pivoted member to be lifted; a counterweight; two members spaced apart; flexible means connecting said pivoted member and said counterweight and engaging and ex: tending between said two spaced members; and a movable member to engage and deflect said flexible means between said spaced members; and means to operate said movable member.

5. A counterbalancing device comprising a pivoted member to be lifted; a counterweight; two sheaves spaced apart; flexible means connecting said pivoted member and said counterweight and in engagement With said sheaves; a support; an auxiliary mem- 10 her guided by said support; a link pivotally connected with said auxiliary member; a sec. ond link pivotally connected With the first link and pivotally connected With the counterweight, said first link carrying a sheave to engage the flexible means between the tWo spaced sheaves t0 deflect the flexible means so as to transfer a portion of the Weight of the counterweight from the lifted member to the support.

RANDALL D. GARDNER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

